An isolation device provides a means for moving a signal from one electrical circuit to another electrical circuit when the two electrical circuits are otherwise electrically isolated from one another. Usually the two electrical circuits operate at different voltages, and thus, must be electrically isolated. For example, consider an application in which a 5V battery-powered controller board is utilized to control a motor circuit operating at 240V. In this example, it is essential to electrically isolate the 240V motor circuits from the 5V controller circuit, while permitting the 5V controller circuit to send or receive signals from the 240V motor circuit. In this type of application, an isolation device may be used to provide voltage and noise isolation, while permitting the information exchange between the two circuit systems. For electrical system with more than two circuits operating at different voltages, a multichannel isolation device may be used.
In an isolated system where two or more signals are transmitted across an isolation barrier, an equivalent number of isolation devices are typically required to transmit the signals across the isolation barrier. The requirement for equivalent number of isolation devices adds to cost. Furthermore, in some cases it may not be feasible to employ two isolation devices in an integrated circuit package due to space constraints. What is need is an isolated communication system where analog and digital signals can be transmitted and received through a single isolation channel.